Mechanism for operating switches



y 1943- s. H. DURBIN 2,318,300

MECHANISM FOR OPERATING SWITCHES Filed Dec. 26, 1941 2 SheetsSheet 2 Z V a l a 63 '1 g l I lNVENTOR 67J4/VlEY/6K 01/65/11/ 6 Patented May 4, 1943 MECHANISM FOR OPERATING SWITCHES Stanley H. Durbin, Brooklyn, N. Y., assignor to E. W. Bliss Company, Brooklyn, N. Y., a corporation of Delaware Application December 26, 1941, Serial No. 424,391

10 Claims. (01. 200-83) This invention relates to improvements in mechanisms for operating switches and more particularly to operating mechanisms adapted to utilize the pressure of liquid in a hydraulic system as the medium for causing such a mechanism to move the operating member of a switch.

The present invention is particularly useful in the operation of electric switches in which an electric circuit may be made, broken, shifted or otherwise varied by a very slight movement of a switch-operating member such as a plunger.

An important object of this invention is the provision of switchoperating mechanisms, of the general character described, which will be capable of rendering long service and of operating a, great number of times without undergoing any substantial wear and tear or other deterioration which might require repairs or replacements.

Another object of this invention is the provision of switch-operating mechanisms which will be responsive to relatively high pressures encountered in a hydraulic system while preventing leakage of liquidfrom the said system.

Another object of this invention is the provision of switch-operating mechanisms of the general character referred to in which precise adiustments may be readily effected to render the said mechanisms responsive to pressures of predetermined value.

Still another object of this invention is the provision of switch-operating mechanisms of the general character referred to in which improved means are employed for constraining the moving parts of the mechanism to very slight movements whereby to minimize wear.

These and other objects and advantages may be derived from the present invention of which, for purposes of illustration, certain preferred embodiments are disclosed in the accompanying drawings, in which: Figure 1 is a substantially central vertical sectional view of a preferred embodiment of the present invention (hereinafter referred to as the first embodiment), on the line l| of Fig. 2;

Fig. 2 is a bottom plan view of the said first embodiment;

Fig. 3 is an end elevation of the said first embodiment as viewed from the right of Fig. 1, an end cover being removed to show. certain parts;

. Fig. 4 is a fragmentary vertical sectional view' substantially on the line 4-4 of Fig. 2;

Fig. 5 is a substantially central vertical sectional view of another preferred embodiment of the present invention (hereinafter referred to as the second embodiment), on the line 5-5 of Fis- Fig. 6 is a top plan view of the said second embodiment;

Fig. 7 is an end elevation of the said second embodiment as viewed from the right of Fig. 6; and

Fig. 8 is a fragmentary, vertical, sectional view substantially on the line 8-4 of Figs. 6 and 7.

Referring to the first embodiment illustrated in Figs. 1 to 4, the principal parts of the mechanism comprise a hydraulic chamber ll adapted to be connected to a hydraulic system, a flexible washer l2, a plunger l3 adapted to react to pressure in said chamber, and a rocking beam I4 adapted to receive such reactions and transmit them to a switch I5 through the medium of a movable operating member of said switch in the form of a plunger Hi. The said mechanism also includes a compression spring I! adapted to oppose such reactions through the said rocking beam, the compression of said spring being adjustable so that the mechanism may be set to respond to different predetermined hydraulic pressures.

All the parts recited are suitably mounted and arranged relatively to one another upon or within a box l8, having integrally formed sides 18a, I8b, an end I and bottom (1, and a removable end 18c and removable top 18!, the two latter being suitably held in place in the complete structure by screws I9, 20, respectively, which screw into portions integral with the body of the box.

The hydraulic chamber H is preferably annu lar and formed within a connection block 2i, which may be fixedly mounted, as by machine bolts 22, to the underside of the box l8 near one end thereof. A passage 23 is provided, affording connection between the chamber II and a hydraulic system. The said passage may be suitably threaded to facilitate connection of a pipe or coupling, or other means of connecting the disclosed mechanism to a hydraulic system.

The plunger i3 is preferably of the same diameter as the chamber ii, and is accurately fitted to reciprocate within a bore 24, formed in a thickened, solid portion 25 of the box I8, in axial alignment with the chamber Ii.

The washer I2 is preferably circular, and is marginally bound in place between the flat surface of an annular shoulder 26, formed in the connection block 2I' at the upper end of the chamber II, and an opposing fiat surface on the bottom of the box IO surrounding the lower end of the bore 24. It will be seen that the said washer defines th upper end of the chamber II and is in position to engage the lower end of the plunger l3.

The upp r end of the plunger 13 extends above and clear of the portion of the box, and upon its upper end is formed a knife edge 21, which engages the underside of the rocking beam l4 within a lateral groove 28 formed toward an end P of said rocking beam. In the top of said beam, at an intermediate point thereon, toward the end P, is formed a lateral groove 29, within which a knife edge 30 on the underside of a fulcrum bar 3| engages the rocking beam so that upward movement of the plunger I3 coacting with said fulcrum bar will impart a rocking movement to the said beam, The fulcrum bar 3| is retained within a bridge-piece 32, which is fixed upon the solid portion 25 by screws 33 disposed at each side of the beam.

The switch I5 is fixedly mounted, by screws 34, or in any other suitable manner, upon a web 35, preferably formed integrally with the box l8, in such position that the plunger l6 of the said switch is adapted to be engaged and operated by the other and (sometimes hereinafter characterl ized as S) of the rocking beam I 4.

The end S of the rocking beam is preferably flattened and extends over a flat upper surface 33 of the web 35, and said surface operates to limit the downward movement of the end S during the rocking motion of the beam l4. The upward movement of the end S during the rock ing of the beam is limited by a cross-pin 31, which extends,'above and across the end S of the beam. within bosses 38, 38, formed along the top of the web 35 at each side of the beam. The cross-pin 31 may be held in place in any suitable manner, as by a cotter pin 39.

The switch l5, as best seen in Fig. 3, is mounted in such a position that the upper end of the plunger I 6, when in its uppermost operating position. extends above the level of the surface 36 and into engagement with the underside of the end S of the rocking beam. The said switch is of a character in which the shifting of the contacts therein from one operating position to another, as, for example, from a closed to an open position. takes place in response to a very slight longitudinal movement of its operating plunger, the

magnitude of such operating movement being so slight that a slight downward movement to which the end S of the rocking beam is limited in the structure as illustrated in the drawings, is sufficient to operate the said switch by moving the switch contacts from open to closed position, or

vice versa, or by otherwise shifting said contacts. Switches of the character employed in the disclosed mechanism may be designed to operate in response to a movement of as little as .001 of an inch and, for the purpose of the present specification, it may be assumed that a switch having this characteristic is employed in the disclosedmechanism.

The spring IT, as best seen in Fig. 1, is preferably arranged to coact with the beam l4 at a point intermediate the fulcrum point of the beam and the end S thereof. At said intermediate point an adjusting screw 40 is threaded downwardly through the said beam and is provided with a locking nut 4|. The ends of said spring seat upon saddles 42, 43. the former of which seats against the bottom of the adiusting screw 40, and the latter of which seats within a hollowed-out part of an adjusting screw plug 44, which is threaded into a thickened, solid portion of the box bottom ltd, the lower end of said screw plug being arranged to extend outside the bottom of the box and having a knurled finger grip 43 to facilitate manipulation of the screw plug 44 so that it may be rotated to effect adjustment of the tension of the spring.

The lower end of the adjusting screw 40 is preferably tapered to a point which seats at the center of a conical recess in the top of the saddle 42, the angularity of the surface of said recess being greater than the angularity of the tapered surface of the screw 4|! relatively to the axis of the latter, so that the said saddle is capable of some circular pivotal movement about said axis.

The saddle 43 is likewise rendered capable of similar circular pivotal movement by being provided with a recess in its underside adapted to accommodate a single ball bearing 41, which works works upon a circular bearing plate 48 disposed within a recess in the lower end of the screw plug 44, the parts referred to being sodesigned that the lower surface of the saddle 43 is spaced somewhat above an adjacent underlying surface of the interior of the screw plug 44. The described mounting of the spring ll assures that during the operation of the device the flexing of said spring will be uniform throughout.

Means are preferably provided for preventing unintended rotation of the screw plug 44, said means comprising a sliding plug 49, which, as best seen in Fig. 4, may be fitted to slide within a slideway 50 formed in the bottom of the structure of the box l8 and extending horizontally to the threads of the screw plug 44. The plug 49 may be corrugated on its inner end complementally to the threads of the plug 44, and should preferably be of relatively soft metal, so that the engagement of the plug with said threads may not cause damage to the latter. The outer end of the plug 43 may be beveled, as at 5! and the said beveled portion may extend within a vertical bore 52, into which is threaded a manually operable wing screw 53, which is tapered at its inner end to the same degree as the bevel on the plug 49. Thus, by tuning a up the wing screw 53, the tapered inner end of the latter is caused to engage the beveled portion SI of the sliding plug, thereby urging the said plug inwardly into a tight engagement with the screw plug 44, so that the latter may not be unintentionally turned.

A suitable threaded opening 54 may be provided in the bottom l8d of the box, preferably at a point immediately below the switch l5, to afford means for connecting to the mechanism suitable electric conduits from within which wiresmay pass into the box l8 and be connected to terminals lSa of the switch I 5. The said conduits and wires are not shown in the drawings, as such a showing is not necessary to an understanding of the invention. The area within the box l8 immediately surrounding the switch I5 is preferably insulgged by suitable insulation material indicated a The exposed portion of the screw plug 44 may carry a pointer 56, and calibration markings 51 may be provided upon the bottom of the box II or upon a suitable index member fixed to the bottom of said box, the said markings being located underneath the path of angular movement of the said pointer and being marked to bear an understood relation to the various pressures in response to which the mechanism is adapted to operate.

In practice. the adjusting screw 40 and the screw plug 44 preferably are first adjusted so that, when the pointer ll registers with a minimum marking on the calibration markings l1. the end S of the rocking beam H is held by the spring I! in its uppermost position and the mechanism will function to operate the switch I! in response to the lowest hydraulic pressure at which operation of the switch might conceivably be desired. When such adjustment is attained, the lock nut ll is tightened and the spring is then in what might be termed a "pre-load" position. Thereafter the mechanism may easily be rendered responsive to a selected higher hydraulic pressure by turning up the screw plug 44 to a suitable extent.

The movement to which the end S of the beam II is limited need be only suflicient to cause the switch to operate on the downward movement of said end S before such movementof the latter is arrested by the surface 38. Such movement of the end S, as a practical matter, may be about .02 of an inch. Observing that, in the first modification as illustrated, the ratio of the lengths of the ends of the beam ll computed from the fulcrum point thereof is about 8 to 1, it will be apparent that satisfactory operation of the mechanism may be derived from an upward movement of the plunger l3 of between .002 of an inch and .003 of an inch.

The lower end of the plunger l3 preferably is substantially flat, and the parts of the mechanism are so designed that the said flat bottom end of the plunger, when not subjected to operating pressure, lies in a plane substantially corresponding to or slightly lower than the plane of the engaging flat surfaces of the upper side of the connection block 21 and the bottom of the box It. Under this arrangement it will be apparent that, regardless of the pressure at which the device may be set to function, the said washer does not flex substantially during the operation of the device. There is, of course, sufllcient distortion or flexing of the said washer in response to the hydraulic pressure imposed upon the under side thereof to operate the mechanism, but such distortion or flexing is very slight indeed and may even be considered as constituting a mere compression of said washer, which compression reacts as a force operating upwardly upon the underside of the plunger I3 in order to operate the mechanism. It may easily be understood that, by strictly limiting the distortion of said washer in the manner described, the wear which might possibly occur therein .would be negligible.

It will also be appreciated that, by restricting the movement of the parts of the mechanism in the manner just described, the possible flexing of the spring I1 is extremely limited, regardless of the hydraulic pressures present in the system to which this device may be connected. Because of such restriction in flexing, and because of the fact that the flexing of said spring is uniform throughout, the said spring will yield satisfactory service' over a long period of time or throughout a very large number of repeated operations without any necessity for replacement thereof.

Referring now to the second embodiment, the various operating parts, instead of being mounted within or upon a box, are assembled as an operating unit about a block 58, and the permissible movement of the various moving parts is somewhat greater than in the first embodiment. As may be olmerved by a comparison of Fig. with Fig. 1, the plunger l3, the beam H, the switch l I and the spring I I are similarly arranged. In considering the differences between said embodiments it may be observed that the spring i1 is provided with only one adjustment, the switch It is pivotally mounted upon the block ll instead of being fixedly mounted thereon, and the. distortion or flexing of the washer, characterized as Ila, is somewhat more pronounced than in the first embodiment.

The lower end of the spring ll rests within a retainer 59 fixedly secured to the bottom of the block 58 by screws Ill. The upper end of said spring, similarly to the first embodiment, seats upon the underside of a saddle l2, and adjustment'of the spring tension is obtained by turning and locking the adjusting screw 40 to the proper extent.

The flexible washer l2a may be preformed substantially to the vertical sectional design shown in Fig. 5 in the manufacture of such a washer by molding or by other means. The said washer is preferably held in place within adjacent complemental recessed portions in the bottom of the block 58 and in the upper side of the connection block Ma. The hydraulic pressure of liquid in the connected hydraulic system may be applied to the underside of the washer 120 through a threaded opening 6| and a small hydraulic chamber lla preferably located coaxial- 1y with the washer l2a.

It will be observed that, except for the mar' ginal areas by which the washer lZa is secured in place, the said washer is substantially coneshaped, the upper end 62 of said some being arranged to extend slightly up into the bore 24. A washer 63, preferably of leather or other material of somewhat similar characteristics, may advantageously be interposed between the top of the washer no and the bottom of the plunger l3. The underside of the washer 63 is preferably complementally shaped with respect to the portion 62 of the washer l2a, so that, even under pressure, the conical shape of the latter is maintained and wear about the margin of the washer lZa is minimized.

The switch I5 is fixed by screws iii to a mounting plate 64, which is pivotally secured at one side thereof to the block 58 by a pivot pin and is held in intimate engagement with the said block at its other side by a cleat 66, which is secured to the block 58 by screws 51. Movement of the mounting plate 84 and of the switch i5 about the pivot pin 65, in order to adjust the position of said switch relatively to the end S of the rocking beam, may be accomplished as best seen in Fig. 8 through the medium of an adjusting screw 68, having a knurled wheel 69 formed integrally with the lower end thereof, said screw being threaded upwardly through and extending above the top of the block 58 at a point therein adjacent the plate 84. The adjusting screw 68 is shouldered, as at I0, and has a reduced portion ll above said shoulder, extending upwardly through an oversize hole 12a in a lug 12, which is suitably flxed upon the plate I at the side thereof remote from the pivot pin 65.

The shoulder 10 is of greater diameter than the hole 12a and thus the engagement of said shoulder with the underside of the lug I2 determines the lower limit of the position of the plate 54. The upper limit of the position of the said plate is determined by a compression coil-spring 13, which extends about the reduced portion H of the adjusting screw and is compressed between the top of the lug l2 and a washer H which is top of the plate 64 extends above the top of the block 58, and the switch I5 is so mounted on said plate that the top of the plunger it, when the latter is in either of its extreme operationg positions, extends above the top edge of the plate 64, so that said plunger may be engaged and operated by the beam ll regardless of the position to which said plate may be adjusted in any practical operation of the mechanism. The disposi- 'tion' of the switch on said plate, however, should related to the spring is employed primarily for establishing a minimum, but nevertheless positive, engagement of all coacting parts of the device exceptingthe switch I5 and its plunger,

and the said adjusting means related to the switch is adapted to permit the variation of the location of the said switch and its plunger with respect to the end S of the beam H.

The said adjustment related to the spring, once made, would seldom, if ever, have to be changed and, hence, might be considered as a permanent adjustment. The said adjustment related to the switch, however, is easily varied so that the mechanism may be made responsive to any predetermined hydraulic pressure which might be encountered in actual practice.

It will, of course, be understood that the compression in the spring I'I increases as the spring becomes further compressed in response to pressure in the chamber Ha, and causes a corresponding increase in the hydraulic pressure at which the switch will operate; hence, the particular position of the switch plunger in the path of movement of the end S of the beam, determines the hydraulic pressure at which the switch will function. Thus, turning the screw 68 up or down will lower or raise respectively the hydraulic pressure at which operation of the switch will occur.

It may be perceived that each of the embodiments described may possess certain advantages under diiferent operating conditions. The use of a washer l2 or In which is impervious to oil and is bound tightly in place permits an arrangement which prevents leakage of oil from the connected hydraulic system, and by employing the disclosed mechanisms, wherein none of the operating parts undergo substantial movement, any possible wear on'such a washer and, indeed, upon any moving part of the device, is greatly minimized.

I It should be understood, of course, that the said two embodiments are shown and explained only for the purpose of illustration, and that the inventive concept may be employed in various structures other than those illustrated and described herein without'departing from the spirit of the invention as defined in the. following claims.

What I claim is:

1. An operating mechanism for a switch having a short-stroke reciprocable operating member, said mechanism comprising a mounting structure adapted to carry the several operating held upon the screw 68 by a cotter pin 15. The,

parts of the mechanism; a lever having a first portion adapted to receive a force for turning the lever about its fulcrum and a second portion adapted to engage and operate said operating member when the lever is tumed; a hydraulic chamber adapted for connection to a hydraulic system; a substantially flat flexible member of oil-resistant material partially defining said chamber and being adapted to flex in response to pressure therein; means adapted to enact with said flexible member and said first portion of the lever to communicate movement of the former to the latter; and a spring coacting with said lever and said motion-transmittingmember to oppose such flexing of the said flexible member, the said flexible member being firmly gripped over substantial marginal areas about substantially the entire periphery thereof, between opposed gripping surfacesof the said mounting structure.

2. An operating mechanism for a switch having a short-stroke reciprocable operating member, said mechanism comprising a mounting structure adapted to carry the several operating parts of the mechanism; a lever having an intermediate fulcrum point demarking a long arm adapted to engage and operate said operating member, and a short arm of the lever; a hydraulic chamber adapted for connection to a hydraulic system; a substantially disc-like flexible member of material which is substantially impervious to oil, said flexible member partially defining said chamber and being adapted to flex in response to pressure therein; means coacting with said flexible member and the short arm of the lever for transmitting movement from the latter member to said short arm to turn the lever and cause the said long arm to coact with and operate .the operating member of the switch; and a spring coacting with the said lever and said movement-transmitting means to oppose such flexing of the said flexible member, the latter being firmly gripped over substantial marginal areas about substantially the entire periphery thereof, between opposed gripping surfaces of the said mounting structure.

3. An operating mechanism for a switch having a short-stroke reciprocable operating member, said mechanism comprising a mounting structure adapted to carry the several operating parts of the mechanism; a hydraulic chamber adapted for connection to a hydraulic system; a substantially flat flexible member of oil-resistant material partially defining said chamber and being adapted to flex in response to pressure therein; and means coacting with said flexible member and said reciprocable operating member to transmit movement of the former member to the latter member; the said flexible member being firmly gripped over substantial marginal areas about substantially the entire periphery thereof between opposed gripping surfaces of the said mounting structure and the said means comprising a reciprocating transmission member having 'a surface coacting with and of substantially the same shape and area as the surface not so gripped, on the side of said flexible member remote from the said chamber, whereby to oppose distortion of the flexible member.

'4. An operating mechanism according to claim 3, further characterized in that the said flexible member is disc-shaped and in that'the said c'o- 5. An operating mechanism according to claim 3, further characterized in that the said transmission member comprises a plunger accurately fitted to reciprocate within a bore formed within the said mounting structure, the said surface of the flexible member which is not so gripped extending over one end of said bore, one end of said plunger terminating substantially at the corresponding end of said bore, and the entire area of one end of said plunger being in engagement with said flexible member.

6. An operating mechanism according to claim 1, further characterized in that adjusting screws are provided coacting with the spring at opposite ends thereof for adjusting the tension of said spring whereby to permit the mechanism to be rendered responsive to different hydraulic pressures.

'7. An operating mechanism according to claim 1, further characterized in that an adjusting screw is provided, coacting with the spring at one end thereof for adjusting the tension of said spring whereby to permit the mechanism to be rendered responsive to different hydraulic pressures, the said adjusting screw extending to the exterior of the device and being manually operable, and a calibrated scale being provided on the outside of the device adjacent the exterior portion of the said screw and adapted, in conjunction with the latter, to indicate the adjustment of the tension of the spring.

8. An operating mechanism according to claim 1, further characterized in that an adjusting screw is provided, coacting with the spring at one end thereof for adjusting the tension of said spring whereby to permit the mechanism to be rendered responsive to different hydraulic pressures, the said adjusting screw extending to the exterior of the device and being manually operable, and means being provided for preventing unintentional movement of said adjusting screw, said latter means comprising a sliding plug adapted to engage the said adjusting screw and a lock-screw adapted to engage and urge the said plug into tight engagement with said adjusting screw whereby to prevent turning of the latter.

9. An operating mechanism according to claim 1, further characterized in that an adjusting screw is provided, coacting with the spring at one end thereof for adjusting the tension of said spring whereby to permit the mechanism to be rendered responsive to different hydraulic pressures, the said adjusting screw extending to the exterior of the device and being manually operable, and means being provided for preventing unintentional movement of said adjusting screw, said latter means comprising a sliding plug, one portion of which is adapted to tightly engage the said adjusting screw on one side thereof and another portion of which is beveled, and a lockscrew having a tapered portion adapted to engage the beveled portion of said plug and urge the latter into tight engagement with said adjusting screw whereby to prevent turning of the latter.

10. An operating mechanism according to claim 3, further characterized in that the said surface of the flexible member is conical and in that there is provided a washer of resilient material which is less resilient than the material of the flexible member, which washer is interposed between the said surfaces of the transmission member and the said flexible member and shaped to complementally engage both such surfaces whereby to oppose distortion of the flexible member to minimize wear or damage thereto.

STANLEY H. DURBIN. 

